1. FIELD OF INVENTION
The invention relates to an alarm setting device, more particularly to an alarm setting device of a table clock which device can be produced by a simple mold and cheap manufacturing cost.
2. DESCRIPTION OF THE RELATED ART
It is a common knowledge that a clock generally includes a counting mechanism consisting of a gear train with calibrated dial and indicating hands. A modern clock even consists of a device which can give out an alarm at a preset time. The device includes a hand rotatable by a connecting wheel ( hereon referred to as a time setting wheel). To set a time, one has to turn the setting wheel in an clockwise direction. Often the hand is rotated beyond a predetermined place, in which situation the hand has to be turned a full rotation in order to reach said predetermined place again.
To remedy this drawback, a new time setting device has been invented, in which the hand to set a predetermined time can be turned clockwise or anti-clockwise directions. FIG. 1 shows a time setting device of prior art model. Accordingly, it includes a setting wheel (B) having a recess (B1) thereon, an hour indicating wheel (C) having a groove with a vertical end (C1)1 and an inclined end (C12), a circular plate (D) having a protrusion (D1) extending downward therefrom and a compressed plate (E) having one edge pivoted to a socket in a housing (A). The protrusion (D1) has a vertical side (D11) and an inclined side (D12). The setting wheel is rotated to stop at a predetermined place, that is, the particular time we wish to be. The hour indicating wheel (C) will rotate in a clockwise direction. While in rotation, the hour indicating wheel (C) pushes the protrusion (D1) of the circular plate (D), moving it in a circle. When the protrusion (D1) of the circular plate (D) reaches the predetermined place of the time setting wheel, the protrusion (D1) falls into the recess (B1), connecting a circuit to give out an alarm, as illustrated in FIG. 2. The connection relationship of the circuit and the alarm system is a known art and is not concerned with the present invention, so that detailed explanation will not be given here.
Because of the tapered side (D12) the protrusion (D1) can get out of the recess (B1) when the hour indicating wheel (C) continues to rotate or when the setting wheel (B) is manually turned in the clockwise direction (shown by an arrow) or alternatively, when the setting wheel (B) is turned in an anti-clockwise direction, as shown in FIG. 2 by a perforated arrow.
A skilled and very precise method is required to make a circular plate with a protrusion (D) having a vertical side (D1)1 which in turn increases the cost of production, since it has a length of only 1mm. Furthermore once the vertical side (D11) is not fully perpendicular to said circular plate, errors in time calculation can occur.